Catch exception from having a bad LangVersion setting in .csproj

If LangVersion is an invalid value and throws an exception, the general
page fails to load. So now we catch this exception and display the
error on the page so the user can correct it.

Fixes VSTS #802073

2 files changed, 21 insertions, 11 deletions

diff --git a/main/src/addins/CSharpBinding/MonoDevelop.CSharp.Project/CSharpCompilerParameters.cs b/main/src/addins/CSharpBinding/MonoDevelop.CSharp.Project/CSharpCompilerParameters.cs
index 9d30f7a21c..ef73cbd84e 100644
--- a/main/src/addins/CSharpBinding/MonoDevelop.CSharp.Project/CSharpCompilerParameters.cs
+++ b/main/src/addins/CSharpBinding/MonoDevelop.CSharp.Project/CSharpCompilerParameters.cs
@@ -227,9 +227,11 @@ namespace MonoDevelop.CSharp.Project
 				return val;
 			}
 			set {
-				if (LangVersion == value) {
-					return;
-				}
+				try {
+					if (LangVersion == value) {
+						return;
+					}
+				} catch (Exception) { }
 
 				langVersion = LanguageVersionToString (value);
 				NotifyChange ();
diff --git a/main/src/addins/CSharpBinding/MonoDevelop.CSharp.Project/CompilerOptionsPanelWidget.cs b/main/src/addins/CSharpBinding/MonoDevelop.CSharp.Project/CompilerOptionsPanelWidget.cs
index 396dc158c6..2085650193 100644
--- a/main/src/addins/CSharpBinding/MonoDevelop.CSharp.Project/CompilerOptionsPanelWidget.cs
+++ b/main/src/addins/CSharpBinding/MonoDevelop.CSharp.Project/CompilerOptionsPanelWidget.cs
@@ -101,10 +101,14 @@ namespace MonoDevelop.CSharp.Project
 
 			var langVerStore = new ListStore (typeof (string), typeof(LanguageVersion));
 			foreach (var (text, version) in CSharpLanguageVersionHelper.GetKnownLanguageVersions ()) {
-				if (unsupportedLanguageVersions.Contains (version) && compilerParameters.LangVersion != version) {
-					// Mono's MSBuild does not currently support C# 8.
-				} else {
-					langVerStore.AppendValues (text, version);
+				try {
+					if (unsupportedLanguageVersions.Contains (version) && compilerParameters.LangVersion != version) {
+						// Mono's MSBuild does not currently support C# 8.
+					} else {
+						langVerStore.AppendValues (text, version);
+					}
+				} catch (Exception ex) {
+					label2.Markup = GettextCatalog.GetString ("C# Language Version (<b>{0}</b>):", ex.Message);
 				}
 			}
 			langVerCombo.Model = langVerStore;
@@ -112,10 +116,14 @@ namespace MonoDevelop.CSharp.Project
 			TreeIter iter;
 			if (langVerStore.GetIterFirst (out iter)) {
 				do {
-					var val = (LanguageVersion)(int)langVerStore.GetValue (iter, 1);
-					if (val == compilerParameters.LangVersion) {
-						langVerCombo.SetActiveIter (iter);
-						break;
+					try {
+						var val = (LanguageVersion)(int)langVerStore.GetValue (iter, 1);
+						if (val == compilerParameters.LangVersion) {
+							langVerCombo.SetActiveIter (iter);
+							break;
+						}
+					} catch (Exception ex) {
+						label2.Markup = GettextCatalog.GetString ("C# Language Version (<b>{0}</b>):", ex.Message);
 					}
 				} while (langVerStore.IterNext (ref iter));
 			}